Saturday, August 22, 2009

A nationwide study of mercury contamination in fish released on Wednesday found this dismal result:

Scientists detected mercury contamination in every fish sampled in 291 streams across the country…

About a quarter of these fish were found to contain mercury at levels exceeding the criterion for the protection of people who consume average amounts of fish, established by the U.S. Environmental Protection Agency. More than two-thirds of the fish exceeded the U.S. EPA level of concern for fish-eating mammals.

The mercury comes from a variety of sources, including coal-fired power plants and mining. Yes, there are natural sources, but the findings demonstrate that concentrations of mercury have increased over pre-industrial times. Here’s a handout from the USGS that explains this.

Fish data is here (Excel file). Smallmouth Bass and Blackchin tilapia caught on Oahu were included in the study. I’m not competent to evaluate the numbers, but the concentration of mercury appeared to be among the lowest in the table if I understand it correctly.

Of course, the fish we purchase largely comes from elsewhere, and the numbers for certain regions of the country are many multiples of the Hawaii data.

Additionally, the USGS report covers fish caught in the USA only. We have no idea what contaminants might be in imported fish unless they have been specifically tested. Even if they are, standing at the fish counter at Don Quijote or even at Whole Foods, we have nothing to tell us what’s in that fish we are contemplating buying for tonight’s dinner.